ES2322848T3 - A CATHETER SYSTEM. - Google Patents

Abstract

A catheter system for introducing and implanting a stent member (3) into the body of a patient, comprising: a catheter member (1) with a first and a second end, the first end having an inflatable part (2) , and being provided a passage that allows fluid communication between the inflatable part (2) and the second end and with means for inflating the inflatable part (2); an expandable stent member (3), capable of permanently deforming when expanded; and a joint formed between the stent member (3) and the inflatable part (2); wherein at least a part of the stent member (3) is detachably secured, thanks to the joint, in the inflatable part (2), characterized in that the joint is formed by heat softening the surface of said inflatable part ( 2); placing the stent member (3) in contact with it and allowing the softened surface to return to a non-softened state in which said stent member adheres, so that the stent member is sunk, at least partially, in The inflatable part.

Description

A catheter system

The present invention relates to a system of catheter for inserting and implanting a stent and comprising a catheter that has, at one end, an expandable part, in its opposite end, elements intended to communicate with media intended to expand the expandable part, and a stent, made of a material to which a permanent deformation is communicated so that maintain an enlarged transverse dimension when the catheter is expanded, said stent being arranged around the expandable part of the catheter and detachably looking at the catheter to Avoid stent movement during insertion.

In case of occluded blood vessels partially, for example, by atherosclerosis, it used to be it is necessary to directly operate the occlusion site to cure a patient suffering from this type of disorder. Such partial occlusion can be dilated thanks to the introduction into the blood vessel of a catheter with an expandable part, and to the expansion of the part Expandable catheter in partially occluded area. But it it is not always enough, since the occluded part can partially be restored or fall back to its occluded state partially. In recent years it has become widespread, so progressive, the treatment of such cases through implantation of a stent (a stent) in the partially occluded part of a blood vessel Once implanted, the stent causes the vessel blood remain dilated. In almost all cases, the patient avoid more severe consequences of such disorder in the future.

Different types of catheters are available with expandable parts. A first type is provided with a part that, due to the pressure effect, it expands thanks to deformation elastic of the expandable part. Often, this guy gets called balloon catheter. A particular embodiment of such a catheter is described in UK 156674. This catheter comprises a reinforcing soul in its expandable part, which presents a design of diamond. The expansion of the expandable part of such a catheter leads I get the simultaneous reduction of the length of that part.

A second type of catheter is made of a substantially non-elastomeric material and equipped with elements that, in the unexpanded state of the catheter, for example, they are rolled / folded around the remaining catheter assembly. The expandable parts will be deployed due to pressure.

On the other hand, there are stents available according With several embodiments. Can distinguish between stents Expandable by pressure and self-expanding stents. Stent type relevant to the present invention is the expandable by pressure, to which the catheter pressure communicates a deformation permanent until the desired introduction diameter is achieved. An example of such a stent is known from EP 312852. The stent described in this document consists of a stent made of a coherent thread

EP 0 615 769 B1 describes a vessel stent intended to be inserted into a vessel, such as a blood vessel, to maintain its shape, and a vessel stent insertion device. The vessel stent consists of continuous fiber filaments of absorbable polymer in vivo , and the filaments are shaped so that they extend in a zigzag along the peripheral surface of a cylindrical member, a tubular member or the like. The vessel stent insertion device places the vessel stent around a balloon-forming part, near the distal end of a catheter, and joins it with a biocompatible material, such as a biodegradable polymer, a water soluble protein or fibrin paste.

The implantation of such a stent is carried out by means of a catheter provided with an expandable part around which the stent is arranged. The catheter, with the stent, is introduced, for example, in the groin area, if the stent has to be housed in a blood vessel of one leg, and is guided, by X-ray surveillance, to the partially occluded site, after which means connected to the catheter apply some pressure to said catheter, and the expandable part of the catheter pushes the stent out, against the wall of the blood vessel. The pressure is subsequently reduced, and then the catheter can be removed from the blood vessel, while the stent, in its expanded state, remains in the part of the blood vessel that needs treatment. The operation is relatively simple compared to the surgical intervention that would be required at the partially occluded site, and therefore is appropriate in many
situations.

The use of balloon catheters to deliver Different types of stents have become widespread in the medical field. Such relatively non-invasive techniques offer many advantages. both patients and surgeons. Despite the advances achieved in this field, there are still different problems in what which refers to preventing unwanted movement of the stent in the balloon not inflated during insertion, placement, and positioning  end of the stent before its expansion and full deployment. With frequency, the stent moves in relation to the balloon during its driving through tortuous vessels and offsets the inflatable balloon, expanding incompletely or improperly. In the worst of cases, the globe can move so that its expansion and Proper positioning is not possible. For example, him EP-A-0442657 discloses a catheter system of the type described above by which the stent is arranged around the expandable part of the catheter, and in which collars or sleeves intended are provided, only, to secure the stent in the end parts of the catheter.

As a result of its collars, this known catheter system has a relatively diameter big. On the other hand, the catheter system is associated with the disadvantage of the risk of the stent separating from the surface of the catheter during the introduction of the catheter system into a blood vessel, with its small radii of curvature, and it cause damage to the blood vessel.

U.S. Patent Document 4,950,227 discloses a similar system, but in which an embodiment is used alternative stent, namely the so-called "mesh stent" whereby the risk of the stent moving away from the catheter surface, but not completely removed. But same as the catheter system described above, the system of catheter known from this US patent is disadvantageous, too, due to the use of collars for the mechanical stent securing and consequent outside diameter increased.

Attempts to solve the unwanted movement of the stent during insertion have included the use of adhesive to bond the stent with the balloon. For example, U.S. Patent No. 5,100,429 uses a photodegradable adhesive to bond the balloon with the stent. In this case, light is used to degrade the adhesive once the stent is inserted into the body. According to this disclosure, the stent used is of the type that is wound around the catheter assembly, which means that the aggregate system then has a relatively large cross section. Therefore, the application fields of the system are limited. In addition, practice has shown that adhesive residues will always remain in the implanted stent, which have to be degraded so that they do not cause blood vessel occlusion. Therefore, implantation is difficult, and the system requires particular adhesives, for example, a photodegradable adhesive, and means, for example, a light source, connected to the catheter to degrade the
adhesive.

So, the fact that catheter systems known incorporating stents have transversal dimensions relatively large, including parts that overlap with ends of the stent, or, optionally, with the entire stent, or being rolled the stent around the catheter assembly, the fields of Application of such catheter systems are limited. Further, there is a risk, associated with known systems, that Adhesive residues adhere to the implanted stent.

Therefore, an object of the invention consists in offer a catheter system of the type that, in a simple way, ensure reliable stent assurance against the catheter and, simultaneously, allow such a catheter system to be designed with a substantially reduced transverse dimension in relation to prior art and without risk of sticking debris from adhesive or materials from the catheter to the implanted stent.

This is achieved thanks to a catheter system characterized in that the stent is adhesively connected with the expandable part of the catheter thanks to adhesive forces between stent and support of less intensity than shear forces applied by the expandable part, which produce their effect on the Adhesive connection when this part expands. The stent is connected, separably, by the connecting line, with the part Expandable catheter thanks to weaker adhesion forces that the shear forces generated in the joint line when the expandable part is expanded, and so that said connecting line fails, from the point of view of adhesiveness, on the surface of the stent, that is, the stent / adhesive interface, during expansion intended to release said stent. The expression "fails from the point of view of adhesiveness ", as used in This document should be understood as indicating interface failure and not in the adhesive matrix itself.

Thus, adhesive communication can be formed thanks to the softening of the catheter surface and the subsequent positioning of the stent against it.

According to the invention, the stent is sunk, at least partially, on the surface of the part Expandable catheter, in its unexpanded state. That way, I know also gets the advantage that the depression formed by sinking the stent on the catheter surface prevents axial displacement of the stent in relation to the catheter and, in addition, reduces the transverse dimension of the catheter system.

The idea of using adhesives to bond the stent with the globe presents inherent problems in relation to the residue of adhesive that may remain once the joint is broken. Such residue, even when it degrades biologically over time, it can present problems and lead to blockage of the vessels more small, as well as other side effects.

The present invention seeks to offer a solution to secure the stent in the inflatable part of the catheter, so that a separable union is achieved without residue risk of adhesive. The union is formed by the material of the inflatable part of the globe. This is achieved by softening the wall outside the balloon and squeezing the stent to penetrate the inflatable wall softened and allowing softened material stick to the stent. Such union, in fact, consists of a joint by hot melt This union can be implemented with different types of stents, including wire stents or stents from cage, as well as porous tubular stents. Adhesion joint it can take place at each point of contact between the stent and the surface of the globe, or can be provided at contact points preselected, separated.

According to another embodiment, which does not fall Within the scope of the present invention, a separate adhesive material, which can be the same material as It constitutes the wall of the globe or other material. But in this case it is it is necessary that the adhesive material has an elastic modulus substantially similar to the balloon module. That way you allow the adhesive remain stationary in relation to the balloon during  the expansion of this one, and to separate of the stent without leaving residues. Although it is not necessary for the adhesive and part modules inflatable (balloon) are exactly the same, it is preferred to maximize the difference between the modulus of elasticity of the adhesive and the modulus of stent elasticity, and minimize the difference between the module of the inflatable balloon and the adhesive one.

This requirement is intended to prevent the adhesive separates from the globe by shear during its expansion and stay on the stent once deployed. If the adhesive has a expansion module that is closer to the balloon module than to the of the stent, the adhesive will tend to remain stationary in relationship with the globe, but it will move at the junction of the line of union in relation to the stent. This can also be illustrated in relationship with figures 8A and 8B. On a contact surface determined between the stent and the surface of the globe wall, different contact points can be identified. During the expansion, all these points begin to move, almost simultaneously, in a shear direction. If the module adhesive elasticity is such that the adhesive points are not they move in relation to the globe, that is, they expand with the balloon, the shear forces will not lift the adhesive from the Balloon surface and adhesive will remain attached to the wall. But at the interface of the junction line between the stent and the adhesive, the contact points now move relative to each other, and, then, the union will be overcome by the shear forces and will separate from the stent, thus releasing the adhesive stent and allowing stent deployment in the vessel without adhesive residue. If the difference between the stent and adhesive modules is sufficiently large, the release of the union between these components can be easily produced, since all points of contact will move substantially simultaneously. This principle can be illustrated in a simplified way thanks to the use of an adhesive bandage on the skin. If the adhesive bandage is removed by very slow exfoliation, it is difficult and painful to remove. But if the adhesive bandage is made of elastomer and can be stretched, it can be easily removed by stretching its ends in opposite directions, thus applying shear forces at ends opposites In this way, the bandage can be lifted with a lot ease, without pulling the skin and using an intensity of force nominal. This is because all adhesive contact points are They move in relation to the skin, which remains stationary.

The present invention seeks to take advantage of such principles by offering a catheter system that includes a catheter member with an inflatable part and a stent member liable to permanently deform when expanded, and secured, detachably, in said inflatable part thanks to a connection, so that when said inflatable part is inflated, the connection is separate from the stent in order to allow member deployment of stent in the body.

In accordance with the present invention, avoiding the incorporation of additional elements, for example, collars, to mechanically secure the end parts of the stent, or, optionally, the entire stent set, and therefore all the catheter system can be constructed with a transverse dimension, that is, a diameter, substantially smaller than in the case of prior art, which is of great importance when the Introduction of the catheter in the patient with its integrated stent is carry out by means of an introductory cover, making possible, also, subsequently select an introducer sleeve with a smaller diameter The size of the introducer sleeve is crucial for the speed of recovery of the patient and his departure from the hospital after treatment As a consequence of this reduction of necessary hospitalization period, the option of using a case narrower introducer contributes to the patient's well-being and Streamlines the operation of the hospital.

The present invention includes a system of catheter to introduce and implant a stent in the body of a patient according to claim 1.

The adhesive bond is formed by the use of Balloon material itself. This is achieved by softening the balloon material, pressing the stent against the softened area and allowing the balloon material to adhere by its points of Contact. As described above, this connection adhesive essentially consists of a fusion joint in hot, so that the stent is attached, detachably, with  The balloon. In this case, as a different adhesive is not used or additional to form the union, there is no residue once the balloon expansion free the stent. According to this embodiment, the modulus of elasticity of the balloon and that of the adhesive they are substantially identical, being the same material. Your modules They are significantly inferior to the stent module. So, the difference between stent and balloon modules is maximized to get the desired result.

Advantageously, the stent sinks into the surface of the expandable part of the catheter with a depth between a twentieth and half the thickness of the stent material, and, more advantageously, between a tenth and a third.

The method of manufacturing the catheter system includes the steps of positioning the stent around the part Expandable catheter, soften the expandable surface of the catheter and apply pressure on the stent to sink it at least partially, on the surface of the catheter.

A mode of implementation particularly simple is to arrange the catheter to mount the stent in its inflatable part in a device containing the stent and introduce a pressurized fluid in the catheter by the elements provided to the effect on the opposite end of the catheter, in order to expand the expandable part of the catheter and squeeze the stent inwards of the device, so that the stent is sunk on the surface of the catheter

Subsequently, the pressure of the fluid in the catheter, so as to reduce, simultaneously, the cross section of the expandable part of the catheter and can Remove the catheter with the stent sunk from the device.

Therefore, the method described above It is simple and effective from the point of view of manufacturing catheters according to the invention, whereby the stent is sunk into the surface of the catheter.

According to another embodiment, which does not fall within the scope of the invention, a separate adhesive is used to join the stent with the inflatable part. The adhesive is selected so that it forms a union that separates only in the stent / adhesive interface and not in the balloon / adhesive interface.

The catheter surface is softened by heating, this process can be controlled easily. By on the other hand, when the softened surface of the catheter regains its steady state, the stent will be attached to the catheter material, which also contributes to ensure the stent during the Introduction of the catheter into a blood vessel. When a adhesive, the catheter surface may be constituted by a adhesive layer of this type.

The invention will now be described in more detail. in relation to the drawings, in which:

Figure 1 is an overview of the system of catheter according to the invention;

Figure 2 is a more detailed view of the expandable part of a catheter in its unexpanded state and that presents a stent secured in it;

Figure 3 is a sectional view of a catheter, in its longitudinal direction, by the expandable part;

Figure 4 shows the catheter and stent of the Figure 2, but with the expanded catheter;

Figure 5 is a sectional view of a catheter for its expandable part, in which the catheter is expanded;

Figures 6A and 6B are more sectional views. details of a catheter in which a stent has been sunk into the catheter surface, and shown, respectively, in the states not expanded and expanded,

Figure 7 is a schematic view of a Useful device for joining the inflatable part of the catheter with the stent,

Figures 8A and 8B are views of a catheter in section, schematic, taken longitudinally by its part expandable, which show the use of a separate adhesive that joins the Stent with the balloon.

Figure 1 shows an embodiment of the system of catheter according to the invention. Catheter system it comprises a catheter 1 provided with an expandable part 2 in its first end, a stent 3 arranged around the expandable part of the catheter, and elements, at the opposite end of the catheter, provided to communicate with means intended to expand the expandable part 2.

Figure 2 is a more detailed view of the stent. 3. The stent is made of a coherent metal thread. This thread is curved and shown as a band wrapped around the catheter in order to form a tubular stent 3.

Figure 3 shows the structure of a catheter 1, which, in a manner known per se, is provided with a part expansible. In this case, the insertion end 4 of the catheter and an inner tubular member 5 are formed in one piece. He insertion end 4 is open between its tip and the member tubular 5. Thus, a guide wire can be used (not shown) for the introduction of the catheter into a blood vessel. In around the inner tubular member 5, and some distance from it, an outer tubular member 6 is provided. The tubular member exterior is made, in part, of a deformable material 7 elastically, preferably a thermoplastic elastomer, and, in part, of a non-deformable material 8.

When the elements of the opposite end of the catheter are connected, for example, with a pressure source of fluid, pressurized fluid will penetrate the space between the members inner and outer tubular, and will cause the material to spread of elastomer 7 and the cross section of the catheter is increased, as shown in figure 4. At the same time, the material of the Stent deforms as the curves move away from each other. The Figure 5 shows a section of a catheter in the state shown in Figure 4

Figure 6A shows how stent 3 sinks on the surface of elastically deformable material 7 of the catheter, in the unexpanded state of the catheter. As the material 7 of the catheter is extended by the effect of pressure, depression partially circular formed on the surface of the catheter, and shown in Figure 6A, it will deform in such a way that the contact surface between catheter and stent will be reduced, as shown in figure 6B. It is indicated, schematically, that a point P, which in the unexpanded state is immediately next to to the stent thread, it will be located at P ', at some distance from the thread of stent, in the expanded state of the catheter. Therefore, it has place a partial displacement of the contact elements, respectively, in relation to the stent and the surface of the catheter. The cessation of the effect of pressure and the consequent Reduction of the cross section of the catheter make the stent remain in its expanded state, shown in figure 4.

Figure 7 shows an end part of a catheter in which a stent is arranged around a part expandable catheter, although the stent is not yet sunk the catheter surface Catheter 1 and stent 3 are introduced into a heating device 9. The temperature in the device heating is maintained between 50 ° C and 250 ° C, preferably, at approximately 150 ° C, and, after a certain period of time, depending on the actual temperature, the catheter surface is will soften. The elements of the opposite end of the catheter are connect, for example, with a source of fluid pressure, and a pressurized fluid will cause the expandable part of the catheter to expand and push the stent against the inside wall of the device So the stent will be sunk into the surface of the catheter. When the pressure is reduced, the cross section of the catheter will be will reduce, after which the catheter and stent may be removed Of the device. When the catheter surface softens and, Subsequently, sinking the stent on the surface is achieved, also, an adhesive connection between catheter and stent, which, in addition, It helps to ensure that the stent is fixed in relation to the catheter during its introduction into a blood vessel. The expansion which takes place during the mounting of the stent on the surface of the Catheter is of an order that only causes its elastic deformation. By therefore, any type of stent expansion during this process of assembly is reversed so that the stent recovers its state not expanded once the catheter system so formed is removed Of the device.

Figure 8A shows the unexpanded balloon and the Figure 8B shows the expanded balloon with inflation forces f_ {I} and shear forces f_ {S} shown by arrows directional at the interface of the bonding line between the adhesive and the stent. Figure 8A represents an embodiment showing the use of a separate adhesive in the form of a band 10 defining a junction line at interface 11 between stent 3 and band 10. The adhesive constitutes the connection between stent 3 and the surface outer balloon 12. In this view, the balloon is in a state not expanded, that is, deflated. The outer surface 12 and the inner surface 13 of the globe define a thickness t_ {1}, which It constitutes the thickness of the inflatable balloon. There are two points, d_ {1} and d_ {2}, marked on the surface of the globe. The distance between these two points, positioned at the corners of the band 10 of adhesive, is designated by 1, which indicates the length of split between the two points. During inflation, represented in Figure 8B, inflation force f_ {1} is applied to the surface internal 13 of the globe so that expansion begins. Simultaneously, as the balloon extends, they occur shear forces f_ {s} in the connection lines of the connection adhesive The elastomer adhesive constituting the band 10 is select so that it presents an elastic module that makes expand along with the globe. During the expansion, the thickness of the balloon is reduced to t_ {2} (less than t_ {1}), and the forces of shears that act throughout the adhesive connection are separated in the junction line 11, causing the stent to disengage from the adhesive and there is a free space 14, so that the balloon can be removed to allow permanent fixation of stent 3 in the body of a patient. There is no adhesive residue left in the stent during balloon expansion There is less movement in the interface between adhesive and balloon that at the interface between stent and adhesive, which indicates that less force is required on junction line 11 to release the stent, since adhesive 10 and stent 2 moved, one with respect to another, during the expansion process.

The material with which the part is manufactured Expandable catheter can be selected from a certain number  of thermoplastic elastomer polymers capable of being inflated But preferably, the expandable balloon is made of polyurethane.

The globe can adopt different configurations and ways to behave in different ways. Further, reinforcement fibers and / or expansion control can be provided in the balloon. Generally, these fibers are embedded in the matrix of the balloon with a helical pattern, so as to prevent expansion beyond a specified limit beforehand. Generally, you are fibers consist of a non-elastomeric thermoplastic material, such as polyethylene or poly (ethylene terephthalate). An example of reinforced balloon of this class is described in the patent of the United Kingdom nº 1,566,674, by which a reinforcement soul is embedded in the expandable globe. The reinforcing soul presents a rhombus or helix configuration whereby a rhombus axis is substantially parallel to the axis of the catheter in which it is fixed The balloon. The expansion of the expandable part of the catheter causes the length of the rhombus axes is modified, so that the length of the second axis, transverse, increase in its state fully expanded in relation to the non-inflated state (without load).

This means that the length of the part Expandable catheter is reduced, that is, a axial movement during expansion whereby the length of the stent is reduced in correspondence with the length reduction of the expandable part of the catheter, so as to favor additionally the release of the stent in relation to the catheter. In addition, this expansion contributes to the partial displacement of contact surfaces, as explained above with reference to figures 6A and 6B. But other catheters will be suitable, also, for use in relation to the catheter system according to the invention. In addition, it is also possible to use All types of expandable balloon stent.

Claims (9)

1. A catheter system to introduce and implant a stent member (3) in a patient's body, which understands:

a member of catheter (1) with a first and a second end, presenting the first end an inflatable part (2), and a step being provided that allows fluid communication between the inflatable part (2) and the second end and with means to inflate the inflatable part (2);

a member of expandable stent (3), capable of permanently deforming when expanded; Y

a union formed between the stent member (3) and the inflatable part (2);

in which at less a part of the stent member (3) is secured, so separable, thanks to the union, on the inflatable part (2),

characterized in that the joint is formed by heat softening the surface of said inflatable part (2); placing the stent member (3) in contact with it and allowing the softened surface to return to a non-softened state in which said stent member adheres, so that the stent member is sunk, at least partially, in The inflatable part.

2. A catheter system according to the claim 1, wherein the joint is formed by expansion of the inflatable part (2) against the stent member (3) in order of sinking the stent (3) into the inflatable part (2). 3. A catheter system according to the claim 1, wherein the joint is formed by application  of a force that causes the stent (3) to sink into the part inflatable (2). 4. A catheter system according to the claim 1, wherein the stent member (3) is made of wires or an expandable tubular member, with perforations. 5. A catheter system according to the claim 1, wherein the inflatable part (2) comprises a thermoplastic elastomer (7). 6. A catheter system according to the claim 5, wherein the thermoplastic elastomer (7) consists  in a polyurethane. 7. A catheter system according to the claim 6, wherein the catheter member (1), except the inflatable part (2), is made of a thermoplastic material not elastomer 8. A catheter system according to the claim 7, wherein said thermoplastic material does not elastomer is selected from polyethylene, poly (ethylene terephthalate) and mixtures thereof. 9. A catheter system according to the claim 1, wherein the inflatable part (2) is made of a non-elastomeric material surrounded by an elastomeric material.